A lot of oceanic life, such as blue mussels, common turtle limpets, mosses, diatoms, oysters, pearl oysters, poriferans, turban shells, sea lettuces, sea squirts, and so on, live in the seawater, and the oceanic life conglutinate on undersea equipments, ships, life belts, harbor facilities, nurseries, fishing nets, and so on, which damages the sea equipments. Particularly, if the oceanic life conglutinate on the bottom of ship, the surface of ship becomes coarse, and requires frequent repair works. In addition, when the surface of ship becomes coarse by 0.01 mm, the fuel consumption of the ship increases by 0.3˜1.0%. This may cause a more serious problem for a large vessel, in which 50% of the vessel operating costs is the fuel expenses.
To prevent such fouling of the sea equipments, an antifouling paint composition prepared by mixing a rosin, a plasticizer, and an antifouling agent with vinyl chloride resin or vinyl resin is conventionally used. However, the conventional antifouling paint composition also induces the seawater contamination because the composition includes mercury or organic tin compound as the antifouling agent. As other antifouling paint composition, U.S. Pat. No. 4,191,579 and British Patent No. 1,457,590 disclose a self-polishing antifouling paint composition in which an organic tin compound such as tributyl tin oxide binds to an unsaturated monomer such as acrylic acid or methacrylic acid to form an ester linkage therebetween. Due to the ester linkage, the antifouling paint composition is slowly hydrolyzed in seawater, and the organic tin compound is slowly released from the antifouling paint composition. The carboxylic group produced by releasing the organic tin compound forms a salt, which makes the antifouling paint to be water-soluble and to be swelled. Thereby, the surface of the antifouling paint is scaled off to reveal a new surface. Such antifouling paint composition is most commonly used for antifouling of the seawater equipments. However, the organic tin compound continuously released from the antifouling paint has a non-target toxicity, which not only induces the seawater contamination, but also destroys the ecosystem. Therefore, it is required to develop a new antifouling paint composition which is effective in preventing the fouling of the seawater equipment induced by the various oceanic life and microorganism, and does not have drawbacks in environmental and hygienic aspects.